With respect to the fourth generation mobile communication system, i.e. the International Mobile Telecommunications—Advanced (IMT-Advanced), ITU-R proposed some requirements on supportable bandwidth, data transmission rate, time delay, mobility and coverage of the system. The requirements on time delay include requirements on control plane delays and requirements on user plane delays. As shown in FIG. 1, the control plane delays include: delay resulted from the transition between idle mode and connected mode and delay resulted from the transition between active state and dormant state under the connected mode; where the delay resulted from the transition between idle mode and connected mode is required to be no more than 50 ms, and the delay resulted from the transition between active state and dormant state is required to be no more than 10 ms.
How to meet the above requirements on time delay is a hot point of the art. Currently used schemes include: decreasing the transmission period of schedule request and introducing contention based uplink data transmission, etc.
3GPP R2-100125, i.e. “Impacts of Contention Based Uplink in RAN2” (Ericsson, 3GPP RAN2 #68bis, Valencia, Spain, Jan. 18 to 22, 2010) discloses a contention based uplink data transmission method in which the base station notifies the user equipment of contention based radio network temporary identifier (CB-RNTI) available in the contention based uplink transmission via a broadcast signaling or a dedicated signaling. When receiving the CB-RNTI, the user equipment starts to listen to the physical downlink control channel (PDCCH), and decodes the uplink resource for contention transmission (CB-grant). The base station determines whether to allocate uplink resources within each sub-frame based on a currently used scheduling algorithm. When the user equipment obtains the CB-grant by decoding on the PDCCH, it starts to process the data for uplink transmission. At the timing corresponding to the CB-grant, the user equipment transmits the data on the physical uplink shared channel. By using the contention-based uplink transmission method, the user equipment needs not to transmit a scheduling request to the base station to request the base station to allocate uplink resources for it. In this way, the time delay of the user equipment resulted from transition between the active state and the dormant state can be reduced in a degree.